For the first time in decades, I'm to be a guest at Thanksgiving dinner. My husband volunteered me to make his favorite dish, peas and baby onions in cream sauce. He loves this, and I do make it every Thanksgiving, and our hosts jumped on it, loving peas, but never having had it in this form.

The thing is, I've never been completely happy with mine. My husband loves it, but when I pinned him to the wall, he admitted, mine is a little runny. It doesn't matter much, people will forgive you anything if you make good mashed potatoes, great dressing, and super gravy (which I do), after that, face it, most barely take a spoonful of the sides.

Well, now I have nothing much to do besides peas and baby onions in cream sauce. The peas and onions are no big deal, but what is the best way to thicken my cream sauce? I've tried wondra flour mixed with butter. Other thickeners besides flour don't hold well at all over the time you need it to (I'm going to have to bring it, ready made, to the group, and maybe get microwave time to heat it). So, unlike some thickeners that break down over time, it has to be able to stand up to some time.

try reversing the thought process - make a nice white roux, add cream until it is thin enough to suit the dish.

the trick of course is to start with enough flour/butter to make the needed volume - "adding more cream" is easy - but too little volume when the consistency is right means making more roux.... (or add some cornstarch slurry, get it back up to temp, add more cream - a bit of a cheat - but it works in a pinch....)

it is important to cook the roux to get rid of any raw flour taste.
it is even more important to get the mix to a mild simmer to ensure the flour/butter has exhausted its 'thickening power' - once you have reached that point any more liquid dilutes/makes thinner - doesn't 'absorb' and create more thickness.

the re-heating does pose some additional challenge. a roux based sauce gets thicker as it cools, and does not go back to the 'thin-ness' when re-heated - so you'll need to make the sauce thinner than what you want in the final product so on reheat it's 'about right' - regrets, that's largely an 'experience' thing. I've found it better to over-thin than under-thin - because a too-thin sauce is still passable, but a too-thick sauce is just gloppy sticky glue....